As known in the art of electrophotographic printers, a photographic surface in the electrophotographic printer is first charged to a uniform potential and then is "exposed" to an image to be reproduced by the scanning of a laser beam thereacross. The photoconductor thereby obtains and electrostatic latent image that constitutes a matrix of discharged pixels on the photoconductor's surface. In a black and white printer, the photoconductive surface is generally developed using a black toner that adheres to the discharged pixel areas to form the image. Thereafter, the toned photoconductive surface is then carried to a transfer station where the image is transferred to a media sheet.
In a multi-colored printer, successive images are developed employing different color toners supplied from corresponding toner modules. Color printing is normally done with yellow, cyan and magenta toner that are applied, in registration, during successive rotations of the photoconductive surface. The printer also generally includes a toner module with black toner.
As the toner in a cartridge, or reservoir, (herein referred to as a cartridge) is expended, the cartridge must be replaced. A toner cartridge must be replaced with a new cartridge of the same color. This, like for like, replacement reduces chances for contaminating the new toner with old toner of a different color. An additional benefit from like for like replacements is reduced printer complexity because the printer does not need to sense the location of each color. However, like for like replacement requires that the user insert the proper color in the proper location.
One approach is to color the toner cartridge to correspond to the toner color. This simple solution does not take into consideration the significant percentage of the population that is color blind. Another approach requires that the printer sense that the correct type toner cartridge has been inserted. One skilled in the art understands that this sensing requires additional hardware and firmware.